Followup for the next unfortunate soul that wants to take this project on! It IS possible to install a Block Heater from the top. I had to remove both upper and lower intake manifolds to have enough room to get the job done. Even with the manifold out of the way I couldn't get my fat hands down far enough to even touch the mounting hole.
With the cable attached I was able to use a coat hanger bent into a "U" on the end to coax the element into the hole!
Once the end is in the hole it was about 3331/3 wiggles using the cable and a long screwdriver to get it coaxed all the way into the hole.
Next challenge was to get the clip to engage, I used one of my long pry-bars that has an angled end to pop the clip on.by prying against the end of the connector.